High diffraction efficiency and flux laminar-type diffraction gratings for boron-K emission spectroscopic measurements

Theoretical study has been performed to explore to enhancement of diffraction efficiency of diffraction gratings around B-K emission (6.76 nm, 183 eV) spectrum based on a scheme to overcoat with materials having high reflectivity and small extinction coefficient (T layer) on conventional metal layer (M layer) coated gratings. In the previous papers we confirmed this effect with a laminar-type Ni-coated diffraction grating overcoated with diamond-like carbon (DLC). In this paper authors examine this effect assuming La, La₂O₃, and LaF₃ layers as the T layer and Ni as the M layer by numerical calculations. As the results, the enhancement of diffraction efficiency is 2.51, 2.28, and 2.01 times with overcoating of the T layers having optimum thickness of 26.8, 29.8, and 29.8 nm of La, La₂O₃, and LaF₃, respectively, compared with a conventional Ni coated grating at a wavelength of 6.76 nm and incidence angle of 85°. (author)